Time delay apparatus



Oct. 7, 1958 c, LlNDAHL 2,855,481

. TINE DELAY APPARATUS Filed Oct. 14, 1954 .'5 Sheets-Sheet 1 300 IOO |20 FIG. I l2 nwENToR CARL LINDAHL ATTORNEY oct 7, 1958 c. LINDAHL 2,855,481

' TIME DELAYA APPARATUS Filed oct. 14, 1954 5 sheets-sheet 2 v62 6o se F|G.2

. INVENTOR l CARL LINDAHL ATTORNEY Oct. 7, 1958 c. LINDAHL 2,855,481

TIME DELAY APPARATUS Filed Oct. 14, 1954 3 Sheets-Sheet 5 INVENTOR CARL LINDAHL ATTORNEY United States Patent Oiice Patented Oct. 7, 1958 TllVIE DELAY APPARATUS Application October 14, 1954, Serial No. 462,170

6 Claims. (Cl. 200-97) This invention relates to time delay apparatus and has particular reference to pneumatic apparatus of the kind in which some desired event such as the closing or opening of an electric circuit is accomplished after the lapse of a predetermined and preferably adjustable time interval following a change in condition of the apparatus.

The general object of the invention is the provision of novel apparatus of the character under consideration which will be simpler in construction and cheaper to manufacture than similar prior devices; which will be smaller and lighter than prior devices, thus particularly adapting the device to aircraft use; which will have novel operating characteristics advantageous for devices of this kind, particularly due to novel switching means and novel means for actuating the switching means; and which will be reliable in operation under various conditions including those in which the device is subject to vibration, and changes in pressure and temperature.

The above and further objects and advantages will appear more clearly from the following description of a device embodying the invention and the accompanying drawings in which:

Fig. 1 is a longitudinal section through a device embodying the invention with the parts in one operative position; n

Fig. 2 is a fragmentary view similar to Fig. l, but with the parts in another operative position;

Fig. 3 is a view taken on line 3-3 of Fig. l with certain parts omitted;

Fig. 4 is a sectional view taken on line 4-4 of Fig. 3; and

Figs. 5 through 8 are various views of the switching means.

Reference is first made particularly to Figs. 1 and 2. The apparatus shown therein comprises a solenoid 6 having leads (not shown), solenoid 6 being wound on a bobbin 8 having an axial bore 10. Bobbin 8 has upper and lower parallel faces 12 and 14, respectively, which are perpendicular to the axis of bore 10, and bobbin 8 is housed in a box 16 conveniently of magnetic sheet metal and having four legs depending therefrom, of which only those numbered 18 and 20 are visible. Box 16 is provided with upper and lower circular openings 22 and 24, respectively, which are concentric with the axis of bore 10.

A grommet-like stop 26 of magnetic material is secured in opening 24 and has a bore 28 coaxial with bore and a flat upper surface 30 located in the lower portion of and perpendicular to the axis of bore 10.

On the top of box 16 is a timing head indicated generally at 32, comprising a base 34 conveniently of sheet metal and having two depending flaps overlapping opposite sides of box 16. Only ap 36 is shown, each flap being secured to box 16 as by screws' 38. The body of base 34 has a concave-upward cup-shaped portion 40, the bottom of which is located on the top of box 16 and is provided with an opening 42 corresponding to opening 22 in the top of box 16. The periphery of portion 40 is shaped to form a horizontal annular surface 44.

Timing head 32 further includes a timing head cover 46 comprising a concave-downwardly body portion 48 a portion of which is shaped to form a horizontal annular surface 50 dimensioned to mate with annular surface 44.

The apparatus also includes a magnet core and spindle assembly including a exible circular diaphragm 52 the periphery of which is adapted to be tightly clamped between surfaces 44 and 50i.

The magnet core and spindle assembly further includes motion transmitting means comprising a magnet core 56, a spindle assembly 58, a coupler 60, a magnet core coil spring 62, a lockwasher 66, -spacer means including three like washers 68, a star spring '70, a diaphragm ring 72, a star spring stop 74, a lockwasher 76 and a screw 78.

Magnet core 56, which is located partly within bore V10, is in the form of a cylinder having an outside diameter slightly less than the diameter of bore 10 and i-s of a length substantially the same as that of bore 10. Thus core 56 is adapted for sliding iit in bore 10. Core 56 further has a at bottom surface 80 adapted to abut top surface 30 of stop 26 with the parts positioned as shown in Fig. 2 but spaced therefrom with the parts as shown in Fig. l. Core 56 is further provided with an axial bore therethrough. The bottom portion of this bore is of smaller diameter than that of the remaining portion thereof, to provide an annular `abutment surface 82 where the bore constricts. The upper portion of the bore is tapped to a predetermined depth as shown.

Spindle assembly 58 comprises a cylindrical spindle 84 of diameter adapted for sliding fit in the bottom portion of the bore in core 56 and bore 28 through stop 26. Secured to the upper end of rod 84 is a head 86 which is cylindrical and of a diameter adapted for sliding tit in the bore through the upper portion of core 56. The upper end of head 86 is stepped to provide an annular shoulder 88, the purpose of which will be shortly explained. The lower end of rod 84 is rounded.

The spindle assembly is assembled with core 56 with head 86 adjacent abutment surface 82 and spindle 84 extending downwardly through the lower portionof the bore through core 56 and bore 28 through stop 26, with the lower end of spindle 84 positioned below stop 26. Thus the spindle `assembly and core 56 are capable ofrelative axial movement.

Coupler 60 includes an externally threaded vcentral portion 90, adapted for screw-threaded engagement with the tapped portion of the bore in core 56, a lower portion 92 rounded at its lower end and of smaller diameter than threaded portion to provide an annular shoulder 93, and a top portion 94 the lower part of which is of larger diameter than threaded portion 90 and is provided with opposed tool-engaging flats (not shown). The upper part of top portion 94 is of still greater diameter and the upper face of top portion 94 is provided with an annular recess 95, the purpose of which will shortly appear.

Spring 62 lies within the bore in core 56, with its lower end in contact with shoulder 88 of rod assembly head 86.

Coupler 60 is screwed into core 56 to the fullest possible extent by means of the tool-engaging ats on upper portion 94 of coupler 60, with lockwasher 66 between the top of core 56 and upper portion 94 of coupler 60. Spring 62 is compressed to an extent between shoulders 83 and 93, and lower portion 92 of coupler 60 lies within spring 62 facing the top of spindle assembly head 86, spaced a predetermined distance therefrom when the apparatus is in the condition shown in Fig. l and abutting head 86 with the apparatus in the condition shown 3 in Fig. 2. Thus spring 62 biases rod 84 downwardly with respect to core'56.

Diaphragm 52, diaphragm ring 72, washers 68, star spring 70, star spring stop 74 and lockwasher 76 are clamped together "between the top surface of coupler 60 and the head of screw 78 which is lbottomed lin a tapped hole `inthe -top Vsurface Vvof coupler 60. The 'shank of screw 78 is longer than lthe tapped uhole bya predetermined amount so "thatthere is a predetermined length `of the shank'abOVe the topsurfaceof coupler '60. This predetermined length is equal to the sum of the thicknesses 'of kdiaphragm "52, washers^68,'star spring "l0, star spring stop 74 and lockwasher 76.

Diaphragm ring 72 is made of sheet metal `including a at washer-like portion and an upstanding 'cylindrical flange atthe Aouter periphery of the washer-like portion, the inside diametercf `the flange as'shown beingl greater than the outside diameter ofthe top surface of coupler 60. The -inside ldiameter of 'the washer portion ris as howns'lightly greater than 'the outside 'diameter of recess Star spring '70 has a central aperturcd'portion with a plurality of downwardly bowed `arms extending radially outward therefrom. When unstressed the outer ends of these arms dene a diameter slightly less than the vinside diameter of the kcylindrical `ange of diaphragm ring 72.

Star spring stop 74 is a ilat'disc of relatively thin metal having a diameter less than the inside diameter of the cylindrical ange ofdiaphragm ring 72. Stop 74 is apertured at lits center to permit passage therethrough of screw 78.

Thus to assemble these parts diaphragm 52 Vis placed 'on the 'top lsurface of coupler 60 with the central diaphragm hole aligned with the tapped hole 'in coupler"60, one of the three washers 68 isplaced `on diaphragm 52 with the washer hole aligned A'with the central diaphragm hole, diaphragm ring 72 is placed on diaphragm 52, star 'spring 70 is placedin ring 72with the central hole of star spring 70 'aligned with the washer hole, the two -remaining washers 68 are placed on star spring 70 with their holes 'aligned with the hole in star spring '70, star spring stop 74 is'placed on the Vtwowashers with its hole aligned with thewasher holes, lockwasher-76 is placed on screw 78 in contact with the head thereof, screw 78 isinserted through the aligned holes, into the tapped holein coupler -bore 10, with Athe periphery of diaphragm 52 lying on surface 44 of timing head base 34, and cover 46 is placed vthereonwith its surface 50 Voverlying thediaphragm periphery. These parts are then clamped together by eight screws '54, of which only two are visible. Inthis condi- Vtion the `underside of the vtop portion of v'coupler`60 en- .gages the upper end of spring 61.

Means attached to timing head cover 46 are provided "for'regulating'rate of lluid flow from the region between ydiaphragm 52 and cover 46 as force is applied tending to move vdiaphragm S2 in the direction 'indicated by the arrow atthe left of Fig. 1 to the position shown in`Fig. l. As shown this means includes va generally cylindrical regulating body 96 coaxial with bore 10 and secured toportion 48 of timing head cover^46 as 'by soldering-to form a fluid-tight joint. Thus a timing chamber A57 is defined by diaphragm 52, cover 46 and the lower surface of regulating Abody 96. The upper surface of body'96 is lapped flat.

The 'fluid flow regulating means also includes a Yregulating dial 98 (Figs. l, 3 and 4) which vis also generally cylindrical having an vaxial clearance hole and a lower lapped surface held against the upper lapped surface of body 96 by 'means of a locking screw 100, a lockwasher 102 Vand anaxially apertured star 'spring 104. Screw 100 yhas a 'threaded shank portion adapted 'for engagement in visible 4 a tapped hole in the top of body 96 as shown and an unthreaded shank portion coaxial with and -of greater diameter than the threaded shank portion.

The regulating means are assembled by screwing screw 100 into the tapped hole in the top of body 96 with lockwasher 102 between body 96 and the Unthreaded shank portion of screw 100, the unthreaded portion of screw 100 passing through the clearance hole in dial 98 and the aperture in star spring 104. Star spring 104 has downwardly bent arms extending radially from the aperture. The ends of the arms engage the'top surface of dial 98 to hold it against body 96, with the lapped surfaces in contact so that uid cannot `pass therebetween and yet dial 98 can -berotated relative to body 96 with sliding movement of the Vlapped surfaces.

The lapped surfaces of body 96 and dial 98 are annular, these parts being provided with central confronting recesses as shown to reduce the areas required to be lapped.

The .lapped surface of dial u98 Alhas Va capillary timing groove V106 therein which registers with a non-capillary aperture 108 through body '96 joining Ytiming chamber '57 and the 'upper lapped surface `-of body 496. Groove `106 is arcuate ybut does "not Vextendv through 360 degrees (Fig. 3). One `end of groove 106 joins fa non-capillary Yslot 110 `('Figs 'and 4) `in dial 98 to effect free .passage ofuid from the adjacent end of groove 106. lAs shown slot 110-is of a depth somewhat -less than -the height Iof 'dial98 andextends radially to lthe'outer cylindrical surface of'dial 98. This detail'of construction is, however, immaterial to` the functioning of the apparatus.

Thusdepending upon the sctting'of dial 98 relative to body 96 a predetermined gyet Yvariable length of groove L106 `is interposed between vaperture -108 and slot `110. The `rate 4of 'fluid ow through the vtiming means -is a function of theinterposed length of groove 106 and in turn a given upwardforce on diaphragm 52 will be able to move diaphragm 521at'a `rate dependent upon the rate of iluid ow 'through thetiming means.

To Yprevent certain settings ofdial -98 Afrom being made one or more stops 112 extending upwardly from body 96 into `the recess vin-dial -98 may ybeprovided adapted to abut vastop 114'extending inwardly fromdial'98 also 4into the recess in `dial 98. Thus for example it may Ybe vdesirable 'to prevent "aperture l108 `from -directly 'registering with .slot 110, or to prevent ydial 98 from being 'set so that 'no portion of groove -106 registers with aperture 10S. In this illustrated apparatus, one stop 1-12 (although only vone'is visible) is vused to cooperate lwith'stop 1114 to prevent each of these conditions, the rst of which would not restrain uid ow 'at all and the second of which would prevent any iluid ilow through the timing means.

The ,rotation Yof-dial "'98 isaccomplished by means of diametrically opposed holes 116 and 118extending downward from 'the top surface of dial 98 to a predetermined depth and 'a similar hole `120 in thehead of screw 10i?. These holes are 'adapted to -receive corresponding tines of 'a key or vother suitable turning tool (not shown).

'The lowersurface of body 96 isprovided-with `a recess `122 to allow 'thehead of'screw 78 to `lie .therein when the apparatus is in the condition-shown infFig. l.

Portions lof the apparatus 4'mentioned so far provide check valve means to allow "fluid to ow freely into-charnber 57 as diaphragm 52 moves downwardly to expand the 'chamber and to prevent Ifluid from leaving chamber k56 as diaphragm `52 moves Ato contract. Ithe chamber, ex-

'ceptthrough the timing means. lToaccomplish this function diaphragm :52is .provided witha plurality of apertures `ofwhich only two, numbered `and 132, are These apertures are positioned on a circle and `are located immediately'above recess 95 in the top snrfacefofcoupler 60. :Star spring stop 74 is likewise pro-- -vided with similar apertures.

When :diaphragm 52 is drawn downwardly 'awav Vfrom the position shown in Fig. 1, a slight vacwim is jcreated in chamber '57, which .causes greater fluid pressure beneath diaphragm 52 to lift valve ring 72 against the resistance of star spring 70, permitting fluid to flow from the region at the lower side of diaphragm 52, between diaphragm 52 and the outer rim at the top of coupler 60, into recess 95 at the top of coupler 60 and through the diaphragm apertures into chamber 57. When diaphragm 52 is then pushed upwardly to return to the position shown in Fig. l, egress of uid through the timing means is sufficiently slow that the fluid pressure differential is reversed and star spring 70 reseats diaphragm ring 72 against coupler 60 to prevent back flow of fluid through the valve.

Located at the bottom of the apparatus is an overcenter switch indicated generally at 124 and including a base 126 of rectilinear configuration and of insulating material. Base 126 is secured to legs 18 and 20 depending from one side of box 16 and to the corresponding two invisible legs depending from the other side of box 16 as by screws 128.

Switch 124 further includes an actuating member in the formfof a lever 138 of spring metal, a contact member 140 and a U-shaped spring 142.

Member 138 has a free end adapted for cantilever movement and a fixed end secured to the top of a block 144 which is in turn secured to the top of base 126 by a screw 146 and a nut 148, screw 146 passing through a vertical bore in base 126. When unstressed, member 138 is bent upward from its xed end toward its free end, to provide a bias tending to move the free end of lever 138 upward at all times. Near the free end of lever 138 is a dimple receiving the lower rounded end of spindle 84.L

Also mounted on screw 146 and between lever 138 and nut 148 is a lever stop 150 of relatively rigid material overlying most of the length of lever 138 and having an edge 152 at its free end positioned to limit upward movement of the free end of lever 138. Thus one terminal position of lever 138 is defined. It will be appreciated that edge 152 is positioned so that with the apparatus in the condition shown in Fig. l, lever 138, which is stronger than magnet core spring62, will not push spindle 84 upwardly relatively to magnet core 56. That is to say, spindle 84 will protrude from magnet core 56 to the fullest possible extent, leaving the maximum gap between the lower rounded end of coupler 60 and the top of spindle head 86.

Contact member 140 comprises two parallel arms 154 and 156 of leaf-spring electrically conductive material. Arm 154 has a movable end and a fixed end secured a predetermined distance above the top of base 126 on a spacer 162 by means of a screw 158 and a nut 166, a Washer 170 being interposed between nut 166 and arm 154. Screw 158 passes through base 126 and between the head of screw 158 and the bottom of base 126 is an electric terminal 172. Arm 156 is similarly mounted on a spacer 163 by a screw 159 and a nut 167, a washer 171 being interposed between nut 167 and arm 156. A terminal 173 is secured between the head of screw 159 and the bottom of base 126. The fixed ends of arms 154 and 156 are located one on each side of lever 138 (Fig. 7), and the movable ends are connected by a connecting member 174 of insulating material.

Lever 138 and member 174 are provided with confronting means holding the ends of spring 142 which is compressed therebetween.

As shown especially in'Fig. 5 contact member 140 carries contacts 176 and 178 on the upper side of the movable ends of arms 154 and 156 (where the arms are connected to member 174), and stationary contacts 180 and 182 are located to contact contacts 176 and 178, respectively, when the apparatus is in the condition shown in Fig. 2. Contacts 180 and 182 also serve as stops defining a terminal position of contact member 140.

Contact 180 is mounted on a strip 184 secured at the 6 proper height above the top of base 126 on a spacer 186 by a screw 188 and a nut 190, screw 188 passing vertically through base 126. A. terminal 192 is secured between the head of screw 188 and the bottom of base 126.

Contact 182 is mounted in similar fashion, on a spacer 194 by a screw 196 and a nut 198. A terminal 200 is secured between the head of screw 196 and the bottom of base 126.

A stop 202 in the form of a metal strip lying on the top of base 126 and secured thereto by a screw 204 and a nut 205 has one end positioned beneath the movable end of arm 154, and a similar stop 206 similarly secured to base 126 by a screw 208 and a nut 209 has one end positioned beneath the movable end of arm 156. Stops 202 and 2,96 define another terminal position of contact member 140.

It will be appreciated that terminals 172 and 192 on one hand and terminals 173 and 200 on the other hand, are electrically connected when the apparatus is as shown in Fig. 2 and are not connected when the apparatus is as shown in Fig. l.

As shown switch 124 further includes another pair of contacts 208 and 210 mounted on spring arms 212 and 214, respectively, secured to the bottom of base 126. Arm 212 is fastened at one end by a screw 216 and a nut 218, screw 216 passing through a vertical hole through base 126 and having its head at the top thereof. Between the head of screw 216 and the top of base 126 is a terminal 220, which is thus electrically connected to contact 208. Arm 212 normally lies flush with the bottom of base 126 and overlies a hole therethrough which is axially aligned with spindle 84. A switch pin 222 is located in this hole and is of a length greater than the thickness of base 126. Pin 222 has a head 224 which is thus adapted to be engaged by the dimple in lever 138, thus to effect downward movement of pin 222 when lever 138 is depressed, in turn to cause pin 222 to depress arm 212.

Arm 214 is mounted similarly to arm 212 by a screw 226 and a nut 228, a terminal 230 being secured between the head of screw 226 and the top of base 126. Arm 214 is spaced from the bottom of base 126 by a spacer 232, and the free end of arm 214 extends beyond the free end of arm 212 and is bent at right angles normally to engage the bottom of base 126 as at 234.

Arm 214 lies directly below arm 212 throughout a substantial portion of the lengths of both. Arms 212 and 214 then bend at right angles away from each other and continue to the places where they are secured to base 126. To attain greater rigidity, arm 212 is additionally secured between the bend and screw 216 by a second screw 236 as shown. Likewise arm 214 is additionally secured by a second screw 238 and a spacer 239.

Thus terminals 220 and 230 are electrically connected when contacts 208 and 210 are in contact (Fig. 2) and not when contacts 208 and 210 are open (Fig. l).

The operation of the illustrated apparatus will now be described. Normally the apparatus is as shown in Fig. l. When current is passed through solenoid 6, the magnet core and spindle assembly is drawn downwardly until further movement is prevented when core 56 engages stop surface 30, to arm the apparatus and compress spring 61. The action of spindle 84 during this movement is in two parts. In the first part the upward bias of lever 138 plus the upward force component exerted thereon by U- shaped spring 142 exceeds the downward force of spring 62, and spindle 84 is therefore held stationary and spring 62 is compressed, until the lower end of coupler 60 engages spindle head 86 (Fig. 2). In the second part, core 56, coupler 60, spring 62 and the spindle assembly move down as a unit, causing spindle 84 to depress lever 138 to its armed position. As lever 138 passes dead center relative to arms 154 and 156 of contact member 140, U- shaped spring 142 snaps from the position shown in Fig. l to that shown in Fig. 2, causing the free ends of arms 154 and 156 to transfer from the positionof Fig. l to .that of Fig. 2, .closing vcontacts 176, 180 .and 173, .182, U- shaped spring 142 'maintaining substantial contact pressure between Athe contacts. This .in turn produces electrical Connection between terminals 172, 192 and 173, 2nd. Simultaneously pin222 depresses arm 2112. until contact 208 meets contact 210, and then arms 212 and 2.1/11- are further depressed as a unit. Since they are initially unstressed, a restoring force is created holding contacts 288 audit@ togetherand insuring a positive conexerts a substantial downward force component on lever 13S, but this component is of .itself yinsufficient to .prevent lever 138 from returning .to theposition ofFig. l.

Also during the .arming .portion .of the cycle, the central portion of diaphragm 52 is pulled downward causing fluid to ll expandingchamber57 through the check valve means vas previously described. The ngersof star spring 7i) are flexed upwardly, and stop 74 prevents overexing.

The apparatus continues in this condition (Fig. 2) until solenoid 6 is deenergized to begin the time delay period. When this occurs, .spring 62 begins to expand, lifting core 56, coupler 60, diaphragm 52 and related parts to eject fluid from .chamber .57 at a rate ydetermined by the setting of the timing mechanism. Spring 61 aids spring 62 in this lifting but is not essential. During this phase .of the operation, the downward force component of spring 62 (acting through spindle 84) plus the downward force component of U-shaped .spring 142. are sufficient to hold lever 138 stationary in .its lower position. Thus rod .84 is stationary and substantial pressure is maintained vbetween all contacts. This movement continues until .the timed period has been substantiallycompleted, at which vpoint the gap between spindle head S6 and .abutment surface 82 has closed and the magnet core and spindle assembly parts have resumed the relative positions shown in Fig. l. Core 56 is then in a critical position, that is, further upward movement thereof is accomplished by a change in the condition ofswitch 124.

Only then does lever 138 move, driving the magnet core and spindle assembly upward as a unit. Spring 61 acts as a booster, augmenting the action of spring 138 after the latter begins to move. Spring 61 is not essential and may be omitted. Likewise contact arms 212 and 214 assist lever 138 but are not essential. As lever 138 approaches .dead center relative to arms 154 and 156 of contact member 14d, U-shaped spring 142. exerts less and less force holding contacts 176, 1b() and 178, 182 closed. At this time, lever 138 and contact member 140 quickly return Vto the positions shown in Fig. l. The portion of the operation described in this paragraph occurs very rapidly, and therefore maximum contact pressure is maintained throughout substantially the entire time delay period. Obviously this is true also as to contacts 26d and 210, since the motion of arm 212 follows that of lever 138 as long as the dimple of lever 138 is in contact with pin 222.

Twostraps of which only one .numbered Etltl is visible are secured to the sides of timing head base 34 and extend upwardly. These serve as means for mounting the entire apparatus to another structure as the inside of .the ton of an hermetically sealed box. i

lt will be apparent to those skilled in the art that many changesmay be made in the apparatus as illustrated without departing from the invention. The invention is accordmgly to be understood as embracing all-apparatus falling within the scope of theappended claims.

Having thus describedmy invention I claim:

l. Time delay control apparatus comprising a body, means for moving said body from a first to a second position and for releasably holding said body in said second position, a switch including an actuating Vmember movable between first and second positions thereof and biased to be normally in its said first position, such that when said body is in its said second position said actuating member is in its said second position, a spring for moving said body from its said second position toward its said first position and providing a bias opposedto that of said actuating member when said body is in `its said second position and for maintaining said actuating vmember in'its said second position during at least a-portioniof the travel ofsaid body from its said second toits said firstposition, and means controlling the rate of such travel.

2. Time delay control apparatus comprising a body, means for moving said body from a first to a second position and for releasably holding said body in said second position, a switch including an actuating member movable between first and second positions thereof, and biased to be normally in its said first position, a linking 'member movable within limits with respect to said body and having a portion movable with said actuating member, so that with said body -in its said Vsecond position said linking member will maintain said actuating member in its said second position, a spring for moving said body from its said second toward its said first position and biasing said linking member against the bias of saidfactuating member for holding said actuating member in its said second position during at least a portion of the travel of said body from its said second yposition to its first saidposition, fand means controlling the rate of such travel.

3. Time delay control apparatus comprising a body, means for moving said body from a first to a second position and for releasably holding said body in said second position, an overcenter switch including an actuating member movable between first and second positions thereof, a contact movable between first and second positions thereof and a toggle member controlling the position of said contact responsive to the movement of said ractuating member from one of its said positions to the other, said actuating member biased to be normally in its said first position, a linking member movable within limits with respect to said body and having a portion movable withsaid actuating member, so that with said body in its said second position said linking member will maintain said actuating member in its said second position, a spring for moving said body from its said second toward its ysaid first position and biasing said linking member against the bias of said actuating member for holding said actuating member in its said second position during at least a portion of the travel of said body from its said secondto its said first position, and means controlling-therate ofsuch travel.

4. Time delay control apparatus comprising a body, means for moving said body from a first to a second posi` tion and for releasably holding said body in said second position, an overcenter switch including an actuating member movable between first and second positions thereof, a contact movable between first and second positions thereof and a toggle member controlling the position of said contact responsive to the movement of said actuating member from one of its said positions to the other, said actuating member biased to be normally in its said first position, a rigid spindle movable within limits with respect to said body and having a portion engaging and movable with said actuating member, so that with said body in its said second position said spindle will maintain said actuating member in its said second position, a spring within said body and engaging said spindle for moving said body from its second toward its .said first position and biasing said spindle against the bias of said .actuating member for holding said actuating memberinits said second position during at least a portion ofthe travel of -said body from its said second to its said .first position, .and means controlling the rate of such travel. v

5. Time delay control apparatus comprising a body, means for moving said body from a first .to -a second position and for releasably holding said .body in said second position, an overcenter switch including an actuating member in the form of a leaf spring movable between vfirst and second positions thereof, a contact movable between first and second positions thereof and a toggle member in the form of a U-shaped spring under compression and controlling the position of said contact responsive to the movement of said actuating member from one of its said positions to the other, said actuating member biased to be normally in its said iirst position, a rigid spindle movable within limits with respect to said body and having a portion engaging and movable with said actuating member, so that with said body in its said second position said spindle will maintain said actuating member in its said second position, a spring within said body and engaging said spindle for moving said body from its second toward its said iirst position and biasing said spindle against the -bias of said actuating member for holding said actuating member in its said second position during at least a portion of the travel of said body from its said second to its said first position, and means controlling the rate of such travel.

6. Time delay control apparatus comprising a magnetic body, a solenoid for moving said body from a first to a second position and for releasably holding said body in said second position, an overcenter switch including an .actuating member in the form of a leaf spring movable between first and second positions thereof, a contact movable between first and second positions thereof and a U- shaped spring under compression to control the position of said contact responsive to the movement of said actuating member from one of its said positions to the other, said actuating member biased to be normally in its first said position, a rigid spindle movable within limits with respect to said body and having an end engaging and movable with said actuating member, so that with said body in its said second position said spindle will maintain said actuating member in its said second position, a coil spring under compression between a portion of said body and said spindle for moving said body from its said second toward its said rst position and biasing said spindle against the bias of said actuating member for holding said actuating member in its said second position during at least a portion of the travel of said body from its second to its first position, and adjustable pneumatic means controlling the rate of such travel.

References Cited in the file of this patent UNITED STATES PATENTS Re. 16,551 Wilms Feb. 15, 1927 2,158,346 Wilhelm May 16, 1939 2,237,705 Kohl Apr. 8, 1941 2,489,381 Lindahl Nov. 29, 1949 2,627,919 Lindahl Feb. l0, 1953 2,630,886 Lindahl Mar. 10, 1953 

